1. Field of the Invention
The present invention pertains to lubrication systems. More specifically, the present invention pertains to lubricating systems in which lubricant is delivered in the form of oil mist to lubricate machinery bearings.
2. Description of the Prior Art
Oil mist lubrication is utilized in many industries to provide continuous, effective lubrication to the bearings of rotating equipment such as centrifugal pumps, electric motors, steam turbines, gear box, blowers, and fans. An oil mist lubrication system typically comprises an air supply for supplying a controlled source of pressurized air, an oil supply for supplying a source of oil and oil mist generation devices connected to the air and oil supply and by which the air and oil are combined to form oil mist for distribution through piping to the equipment. The oil mist continuously bathes the bearings of the equipment and maintains a slight positive pressure in the bearing housing to reduce contamination from outside sources. If the lubricating system functions properly, bearing life is extended, equipment downtime and maintenance costs are reduced.
Efficient operation of an oil mist system requires that the equipment receive a reliable continuous supply of lubricant while minimizing two important variables: the amount of oil consumed and the amount of spray mist escaping to the outside environment. When oil mist is generated the oil is atomized into very fine particles and can be conveyed long distances in a properly designed header system with minimum wetting out on the walls of the pipe in which it is being conveyed. These fine particles, referred to as "dry mist", must be converted into larger particles, known as "wet mist", in order to wet out on the metal surfaces of the equipment being lubricated. This is accomplished by passing the mist through a specially designed restriction orifice known as a reclassifier. The reclassifier reduces turbulence in the stream to convert small particles into larger ones before the mist enters the equipment bearing housing. These reclassifiers serve the additional purpose of metering the amount of lubricant to each bearing to avoid over or under lubricating. Some oil mist particles, particularly the smallest ones, do not wet out on the metal surfaces of the equipment being lubricated. Instead, they sometimes pass through the bearing housings and are vented into the atmosphere. Thus, supplying sufficient oil without over consumption and minimizing stray mist contamination of the environment are important considerations in any oil mist lubrication system.
In recent years, oil mist lubrication systems have been provided with microprocessor controls by which the various conditions of the air supply, the oil supply and oil mist may be monitored and controlled. Such monitoring and control improves the reliability of the oil mist supply, allows faster and more accurate problem identification and provides tighter control over operating variables, thus eliminating many of the problems of the prior art. Such a system is described in U.S. Pat. No. B1 5,125,480. Oil mist generators suitable for use in such systems typically provide heated air from the air supply and warm oil from the oil supply to the vortex of a mist head. Air enters the vortex creating a negative pressure by which oil is drawn into and disbursed into the air as fine oil mist droplets which are discharged into an air space above an oil reservoir for eventual distribution through piping to the equipment to be lubricated.
Even though substantial strides have been made in oil mist lubrication systems, further improvements are needed. For example, if the generation of oil mist is interrupted for any of a number of reasons, it may be necessary to shut the system down for repairs or adjustments to correct the situation. This may result in periods of time when the equipment is not being lubricated. It may even require that the equipment be shut down. Furthermore, if a number of pieces of equipment are being lubricated and some of the equipment is removed or shut down or additional equipment is added to the system, it may be necessary to change the capacity or output of the oil mist generator. In many cases this may require changing out the entire mist head. In addition more compact and efficient means of heating the air and oil prior to entering the oil mist head would be desirable.